Moistening device for printing-presses



W. B. PITKIN.

MOISTENING DEVICE FOR PRINTING PRESSES. APPUCATION FILED DEC. 17, 1917.

1,335,025. Patented Mar. 30,1920.

l 20 g: E i j I i I avwe WALTER B. PITKIN', OF NEVT YORK, N. Y.,ASSIG-NOR TU IPLANOGRAPHIG EQliJ'IPMENl. GUMPANY, INCORPORATED, OF NEWYORK, N. Y., A. CORPORATION OF NEW YUR'K.

MOISTENING DEVICE FOR PRINTJENEt-PRESSJEQ.

nuances.

Specification of Letters Patent.

Patented ltllar; 8d, l dtl.

2 '0 aZZ whom it may concern:

Be it known that l, WALTER lB. PITKIN, a citizen of the United States,and a resident of the city, county, and dtate of New York, have inventedan improvement in Moistening Devices for Printing-Presses, of which thefollowing is a specification.

My present invention relates to apparatus of the general type shown anddescribed in my co-pending application, Serial No. 207,448, filed on thesame date as this, in which a printing surface, such as a planographicor lithographic or other plate, is moistened by the application of steamapplied through a series of jets, which case l[ have designated as (JaseA; and also my other parallel pending application, Serial No. 207,451,filed on the same date as this application, which ll call Case C.

lin general, the two applications referred to contemplate respectivelythe use of steam derived from an outside source, and the use of a tankof water which is brought to boiling point, by preference by an insideheating apparatus; as I have explained in one of these cases, I considervapor of any suitable liquid as within the scope of those applications,as I do of this. The present case, which I call Case B,however,'embraces features of novelty not shown in those in that itprovides means operating without physical contact for sealing themoistening tank, which is placed adjacent to the impression cylinder ofthe press; that is, without physical contact between the plate on therotating cylinder (or other impression device) and the sealing means.The plate which I have especially in mind (although my invention appliesto any form of printing device in which the paper, or type face ofwhatever kind may be selected, may be dampened in order to get a goodimpression) is a zinc or aluminum plate or process cut, and espe ciallythe type of plate now known in the trade as planographic. In these, asis generally known, an ink receiving design is formed by the use ofcertain classes of as phaltic compound which are 'suliiciently rigid tomaintain all of the points and lines necessary for the design and totransfer the ink properly tothe paper, but which do not resist abrasionfrom any form of sliding contact wlthout impairlng the printing quality.

rying the plate-moistening means adjacent thereto, and sealing means forthe closure between the printing cylinder and the moistening means,operating to maintain a substantially complete seal without physicalcontact between the plate and the sealing means; and at the same time ameans is provided for producing a rapid condensation and cooling uponthe printing surface and for the removal of globules and surface water,through the application of air seals to the closure between themoistening device and the tank. Une of the means which have illustratedis a series of air-jets disposed adjacent to the closure, the air beingdirected against the opening at a pressure sufficient to counter-balanceany pressure which may be generated within the moistening tank. Othermeans consists of forming the edge of the moistening tank insuch a wayas to make an air dash-pot effect, preferably by forming a series ofsquare shouldered longitudinal grooves in the abutting edge or surfaceof the tank Where itadjoins the cylinder. It is of course contemplatedthat this closure shall be made as narrow as possible so that the platemay pass the same with the least possible margin. The accompanyingdrawings show,

In Figure 1 a sectional view, partly diagrammatic, of my improvedmoistenin-g.

device, I I Fig. 2 a plan of the parts shown in Fig. 1. Fig. 3 a detailof a method of forming the closure of the tank with a pneumatic dash-.

pot.

Fig. 3 an alternative form of the latter.

It will be understood that my invention is applicable to various formsof printing presses and that it is not necessarily limited to a presscarrying the forms upon a cylinder, although I-have illustrated myinvention in connection with an off-setpress; and it will also beunderstood that the specific form of my invention illustrated in thedrawings and described herein may be greatly varied, without departingfrom its essential principles or the spirit of my invention, thedrawings being illustrative merely of an operative form of my device andindicating one of the many ways 1n which it may be applied.

Referring to Figs. 1 and 2 of the drawings, 1 indicates a form cylinder,that is, the cylinder which carries printing surfaces, whatever theirnature, such as planegraphic plates, etc., and which is inked by i thecurvature of the cylinder 1, at one of its sides. The housing 7 isprovided with means for introducing steam into theinterior thereof,which means may be the jets 8 supplied by the stea pipe 9. The steampipe 9 is provided with a suitable steam cutoff and regulatingapparatus, such as the globe valve 10. The steam jets 8 are mountedradially to the form cylinder 1 and are thus directed toward the face ofthe plate I upon the cylinder 1. They may be adjusted towardand awayfrom the plate by any suitable adjusting apparatus such, for instance,as the yoke 11, which is turned upward at each end and extends acrossthe width of the housing. The steam pipe 9 is attached to the upturnedends of the yoke and the ends of the yoke are prolonged so as to coverthe --slots 12, within which the steam pipes move. Thumb screws 13 areprovided for moving the yoke. They are held against longitudinalmovement in the yoke 11 and are in threaded engagement with the boss 14mounted upon the housing 7. By means of jets 8, steam may be directedagainst the plates of the cylinder 1 at a velocity and under a pressuresuflicient to cause it to penetrate the minutest depressions in theplate 1 and to thus effectively moisten it.

Owing to the relatively large mass of the cylinder 1, condensation ofthe steam to some extent takes place, thus covering the v plate withwater. Mounted upon the housing 7 are the air jets 15, preferablyarranged to discharge upon the surface of the plate as it leaves thehousing 7, due to the rotation of the cylinder 1, and pointed in adirection substantially tangential to the cylinder 1.

- The jets 15 preferably dischar e, as shown in Fig. 1, into the'openingTietween the upper edge of the housing 7 and the cylinder 1. Thedischarge of air thus causes a rapid condensation of the steam upon theplate, by rapidly conducting the heat away from the plate and performs anumber of other functions, among which are, preventing the steam fromescaping from the housing 7, by driving it back into the housing,

. cooling the plate, removing any globules or air bubbles which may beadhering to the plate, distributing the water of condensation over thesnrface of the plate, removing any surplus water of condensation andcausing the water to flow over the plate, thus effectively covering anyportions of the surface, -to which water has not adhered. The jets 15may be of any suitable size and shape, and are preferably arranged atintervals across the entire width of the plate.

They may be directed at any suitable angle or at varying angles" withrespect to the longitudinal axis of the plate or direction of rotationof the cylinder, and are supplied with compressed air at suitablepressure, throughthe pipe 16, which is supplied with a regulating valve17 and is connected with any suitable source of air pressure.

The pipe 16, carrying the jets 15, may be adjusted toward and away fromthe cylinder 1 and housing 7 by any suitable means, such as theadjusting screw 18, which is in threaded engagement with the arm 19,carrying the pipe 16. Arm 19 is hingedly mounted, as at 20, upon thehousing 7.

Located below the housing 7 is a trap 21, which is adapted to catch anysurplus water of condensation.

The operation of my improved device is as follows: Steam is fed to theapparatus through the steam pipe 9, discharging through the jets 8 uponthe plate and filling the interior of housing 7 with the steam, atsubstantially atmospheric pressure. The rotation of'the cylinder 1carries the plate, which has been subjected to the action of the steam,into the zone of action of the air ets 15, which causes a rapidcondensation and a spreading of the water over the plate, WlllCll hasbeen described above. Any surplus water will run down into the housing 7or trap 21, from which it may be drawn.

In Figs. 3 and 3, I show a means of makng the seal between the tank 7and the cylinderl by means of a pneumatic dash-pot. It 1s obvious thatthe forms of closure here shown may be employed in connection with theairets 15, if desired; or under suitable conditions they may be employedalone. a It 1s further obvious that this form of construction may beused with the devices shown in my parallel pending applications alreadvreferred to in this case, and I do not by the clalms made mean toexclude such modifications. In the figures now referred to, 7

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panacea rectangular groove 22; these are by preference interrupted atintervals by partitions 22 This lip may be conveniently formed of asingle casting and only the portion of it adjacent to the cylinder needsto be finished, the finished surface being concentric With theimpression cylinder, and as close to the plate as possible. The effectoi the grooves is to cause eddies due to the motion of the air or steamunder the pressure in the tank, and also from the centrifugal forceimparted to it by the rotation of the cylinder, the steam or vapor beingentrapped in the slight recesses in the design on the plate, escapinginto the grooves 92%, and there setting up eddies which create a backpressure, as is understood. l lo similar device is needed in connectionwith the closure upon the other side out the tank, though it might beused if desired; because the motion or the cylinder is inward toward thetank and centrifugal t'oroe will ordinarily suffice to pr vent the exitof steam or vapor, in conjunction with the trough 21 already referredto.

In Fig. 3 I have shown another shape for the grooves of the pneumaticseal. In these the lower or entering wall 23 of the groove is formed ata-slight angle, so that steam or vapor may more conveniently enter thegroove where it will set up a rotary move ment creating a back pressureagainst the wall 24. @t course other forms of grooves may be used andthe invention may, in this respect as in others, take many forms.

What I claim is:

1. A moistening device for printing presses comprising, in combinationwith a printing plate, means for first subjecting the plate to steam andthen subjecting it to an air blast.

2. A moistening device for printing presses comprising, in combinationwith a printing plate, means for first subjecting the plate to steamthroughout substantially its entire Width and then to a plurality ofblasts of air, at intervals, throughout substantially its entire width.

3. In a device oi? the hind described, a ro-v tat-able form cylinder, aprinting plate mounted thereon, a housing in close pro imity thereto,means for introducing steam into the housing, and means for subjectingthe plate to a blast of air as it' leaves the housing, during therotation of the cylinder.

t. In a device of the kind described, a rotata'ble form cylinder, aprinting plate carried thereby, a stationary housing mclosing a portionof the surface of the cylinder,

means for introducing steam into the housand means for sub ecting theplate to a blast or air at a plurality of points as it leaves thehousing, during the rotation of the cylinder.

5. In a device of the kind described, a rotatable torm cylinder, aprinting plate tit carried thereby, a stationary housing inclosing aportion of the surface of the cylinder, a plurality of steam jetslocated within the housing and discharging. toward the plate, and aplurality of air jets discharging adjacent thereto.

"6.. In a device of the kind described, a rotatable form cylinder, aprintingplate carried thereby, a stationary housinginclosing a portionof the surface of the cylinder, a plurality of steam jets located wit inthe housing, adapted to discharge steam in the direction of the plateand adjustable toward and away from the plate, and a plu rality or airjets located outside of the houstoward the plate, outside of the housingand r ing, adapted to discharge air toward ,the

- jets ofsteam toward the plate, in a direction substantially radiallyto the cylinder, and means for directing a plurality of jets of airtoward the plate substantially tangen-- tially to the cylinder.

9'. In a device of the kind described, a form cylinder, a printing platemounted thereon, a housingiin close proximity to the plate, means withinthe housing, for direct-- ing a plurality of jets of steam toward theprinting surface of the plate, in a direction substantially radially tothe cylinder, and means, external tothe housing, for directing aplurality of jets of air toward the print ing surface of the plate, in adirection substatially tangentially to the cylinder.

10. In a device of the kind described, a

lllti lltl rotatable form of cylindena printing plate mounted thereon, ahousing in close prorimity thereto, the housing containing steam orvapor, and means for closing the open ing between the housing and thecylinder without physical contact between them.

11.. In a device of the kind described, a rotatable cylinder and aprinting plate mounted thereon, a housing in proximity to the cylindercontaining steam or vapor under pressure, means for creating a backpressure between the cylinder and the edge of the housing necessary toprevent the escape of the steam or vapor.

12. In a device of the kind described, a rotatable cylinder having aprinting surface carried thereby, a housing adjacent to the cylinder andcontaining steam or vapor, and

a pneumatic seal maintaining the closure presses comprising, incombination with a between the housing and the printing surprintingplate, means for dampening the face. plate, and means for removingsurplus water l3.'In a device of the kind described, ,a therefrom,comprising means for subjecting 5 5 rotatable cylinder havinga printingsurface the plate directly to the separate and succarried thereby, ahousing adjacent to the cessive action of steam and of an air blast.cylinder and containing vapor or steam, and In testimony whereof, I havesigned my a pneumatic seal maintaining the closure bename to thisspecification this first day of tween the cylinder and the exit wall ofthe December, 1917. 10 housing.

14. A -moisteningdevice for printing I WALTER B. PITKIN.

